Abstract LB-246: Identification of novel direct targets of miR-19a in MCF-7 breast cancer cells

Abstract

Abstract Background: MicroRNAs (miRNAs) are small non-cording RNAs (20-23 nucleotides) that negatively regulate gene expression at post-transcriptional level by interacting with 3′UTRs of their target mRNAs. Aberrant expression of miRNAs in cancer indicates that miRNAs play key roles in human cancers acting as either oncogenes or tumor suppressor genes depending on their targets. The miR-17-92 cluster, including miR-17-5p, -17-3p, -18a, -19a, -20a, -19b and -92-1, located on C13orf25 is well known as oncogenic miRNA, which is overexpressed in lung cancer, malignant lymphoma and breast cancer. However, few data have been collected about the targets of miRNAs, including miR-17-92 cluster, and their roles in tumorigenesis. By using a proteomic approach, we identify novel direct targets of miR-19a. Methods and Results: MiR-17-92 expression profiling was performed in a subset of 32 of cancer cell lines by TanqMan Real-time PCR, and MCF-7 breast cancer cell line was identified as a miR-17-92 cluster overexpressed cell line. To detect candidate target proteins for miR-17-92 cluster, we transfected MCF-7 cell with antisense oligonucleotides against miR-19a, -20a and -92-1 and then performed two-dimensional protein electrophoresis (2-DE) and differential display analysis in protein extracts of MCF-7 which was knocked down of endogenous miR-17-92 by antisense oligonucleotides. Of the 1455 defined valid protein spots, 146 distinct proteins changed 1.5-fold their expression. 135 proteins were identified as candidate target proteins for miR-17-92 cluster by LC-MS/MS. To determine direct targets of miR-17-92, bioinformatics analysis, luciferase assay and western blotting analysis were performed as validation studies. Conclusions: Our results of exhaustive analysis revealed significant differences in the proteomic profile between anti-miR-LNA treated and non-treated MCF-7 breast cancer cell line. Among these candidate target proteins of miR17-92 cluster, we identified novel direct target of miR-19a. To better evaluate the role of miR-19a and the target gene, further studies of gene function are being performed now. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-246.